1. Field of the Invention
The present invention concerns a process for the coking of coal with high swelling pressure characteristics in a “non-recovery” or “heat-recovery” coke oven whereby a coke oven bank composed of coke oven chambers arranged in a row is used for the cyclical coking of coal and a quantity of coal pre-heated to a specific temperature is introduced into the coke chamber to be filled at such a load height as to allow the swelling pressure arising due to coking to be released into the gas compartment over the coke cake, so that the coke oven chamber walls surrounding the coke oven chamber can be relieved of the swelling pressure arising during coking. The invention also concerns a device with which this process can be executed.
2. Description of the Related Art
During the coking of coal, substantial pressure known as swelling pressure arises. This is exerted on the coke oven chamber walls, subjecting the coke oven chamber walls to substantial mechanical stress. Coke oven chamber walls are frequently fitted with an elaborate cross-anchoring system consisting of anchor stands, wall shields, chamber frames, bias springs and anchors. An example of a cross-anchoring system for coke oven chamber walls can be found in WO 2009141086 A1.
Swelling pressure arises during the coking of coal in the so-called plastic zone of the coke cake due to the splitting of the volatile coal components and tar, and tar seam formation arising from the meeting of plastic zones. Swelling pressure is caused by what is known as internal gas pressure, which arises in connection with the dilation and contraction of the coal. The internal gas pressure is exerted on the coke oven chamber walls via the already coked coal, as the coke first forms near the walls due to the hot coke oven chamber walls. During the coking of coal, swelling pressure can arise that is high enough to damage the coke oven chamber walls. Experience has shown that maximum swelling pressure is reached at approximately 75% of operating time, defined as the period between two loadings. As the bias springs of the cross-anchoring system serve to absorb the swelling pressures, they must be pre-stressed to a high degree, and often precisely adjusted in order to prevent damage of the coke oven chamber walls by the swelling pressure.
This entails considerable economic expense. Furthermore the coke oven chamber walls must be repaired frequently due to the influence of swelling pressure if the cross-anchoring system is improperly adjusted or has not been maintained throughout the life of an oven. Because the amount of swelling pressure depends primarily on the type of coal or mixture of types of coal used, severe limitations are often placed on the type of coal that can be used for coking. Therefore, from the very beginning such coals cannot be used for coking that are particularly well-suited for the intended use. It is also possible to reduce the swelling pressure by introducing additives to the coal to be coked. Examples of these are coke breeze with a high content of volatile components and inert dull coal. However, introducing additives is not always desirable as they may also have an undesirable effect on the utilisation processes. Finally, the coking speed also depends on the moisture content, the content of volatile coal components, the height of the load and the load weight.
At the same time, during loading the coal that is fed in must always be levelled after loading with a mechanical levelling bar to convert the conical load into an oven load with a uniform height. This homogenises the coking process. The levelling bar is introduced into the oven laterally through levelling holes in the oven door. This entails a complex design and construction.